Role of water in animal health and productivity

Dear Dr Othieno, Thank you so much for the weekly training you provide to farmers. I never miss reading your informative articles. I am a dairy farmer with four dairy crosses here in Kajiado. I would greatly appreciate it if you could provide us with some information on water and its impact on animal health, what determines daily water intake, and some precautions that we farmers need to keep in mind. Mary Wambui, Kajiado.

Thanks so much, Mary, for the question and for the compliments. Water is a core nutrient without which the health, growth, and productivity of an animal are negatively impacted. The intake of water differs from one animal to another, type of feed taken, ambient temperature, level of production, stage of growth, level of physical activity, health status, and quality of the water.

Drinking water is a major source through which animals get water for their bodily use, while feeds and metabolism are other sources of water. Water given to animals should be fresh and clean. There is a tendency by farmers to overlook the quality of water they give to their animals. A dirty water trough can be a source of dangerous bacteria such as E. coli or salmonella. Water with an odor or bad taste may not be palatable to an animal and will also result in reduced feed intake.

Water is not only required for vital bodily processes like digestion and the subsequent transportation of nutrients throughout the body, but also for the elimination of body waste through feces and urine, and for milk production. Additionally, it plays a role in regulating the body temperature (thermoregulation). Water also constitutes about 75 per cent of the body.

Cows being milked will require a lot of water, about a 50 to 70 per cent increase compared to when they are not producing milk. About 2-4 liters of water are required to digest 1 Kg of feed, and lactating animals need 3-5 liters of water to produce one liter of milk.

Physical activity, for example, animals that graze freely in ranches, will need more water compared to zero-grazed animals. Feeds rich in proteins and salts or dry in nature, such as hay, will result in an increase in water intake.

In hot weather, animals counter heat stress by consuming lots of water, which they use to transfer excess heat to the environment through sweating and panting. When these animals requiring more water are not provided with it, it results in stress, reduced production, subsequent reduction in further feed intake, and hence reduced production. Animals will usually alternate between feeding and drinking water. Water intake can be optimised by having several drinking troughs in ranches or by offering it ad-lib (throughout) in a zero-grazing unit. Where many animals are kept in a unit, a larger water trough or many of them will also help less-dominant animals to have easy access to water. When water is scarce, the dominant animals will take a lion’s share and leave the others thirsty.

Water in calves plays a role in the development of the rumen. Research has shown that calves with good access to water grow and perform better in life compared to those with less access. But care should be taken as calves are also easy victims for water toxicity when they consume a lot of water. For mature cattle, the rule of thumb is for them to have unrestricted access to good-quality water.

It should be noted that poor-quality water can be a source of many diseases, most of which are fatal.

[Dr Othieno is a veterinary surgeon and currently the head of communications at the Food and Agriculture FAO-Kenya. The views expressed here are not necessarily those of FAO but his own]